(1) Field of the Invention
The present invention relates to a rotary hole punching die assembly and a hole punch insert locking arrangement for such an assembly. In particular, the invention pertains to a rotary hole punching die assembly comprised of a plurality of hole punch inserts, a punch wheel, a retainer ring, a clamping collar, a key, and a rotary mandrel. The plurality of punch inserts are assembled on the punch wheel and are retained on the wheel by the retainer ring. The punch wheel with mounted inserts and the retainer ring are then assembled with the clamping collar and key on the mandrel and are secured on the mandrel by the clamping collar and key.
(2) Description of the Related Art
Prior art rotary hole punching die assemblies commonly employ an annular collar that is secured in an adjusted position on a rotary mandrel. The collar is typically formed with a plurality of holes that extend radially into the collar from its periphery. A plurality of hole cutting punch inserts are inserted into the plurality of holes in the collar's periphery. Each of the inserts are radially adjusted so that they all extend a desired radial extent from the collar periphery. Set screws associated with each of the radial holes in the collar secure each of the individual hole punch inserts in their radially adjusted positions in the collar.
The rotary mandrel on which the annular collar of the prior art hole punching die assembly is mounted is commonly formed from a solid metal cylinder. The annular collar of the prior art hole punching die is slip fit over the mandrel and secured in a desired axial position thereon. The mandrels are formed with journal shafts of reduced diameters protruding from their opposite ends for mounting the mandrel for rotation on a hole punching press. A timing gear is mounted on one of the journal shafts.
The timing gear meshes with a gear on an anvil roll of the press. The anvil roll gear drives the timing gear and causes rotation of the mandrel and the hole punching die assembly mounted thereon. The rotation of the mandrel and hole punching die, the anvil roll, and other operations performed by the rotary cutting press operate in synchronism due to the meshing of the anvil gear with the timing gear.
In prior art rotary die cutting presses employing rotary hole punching die assemblies like that described above, the rotary mandrel, with the hole punching die assembly secured thereon, is mounted parallel to the rotating anvil roll on the press. The hole punching die assembly and anvil roll rotate against each other as a web of stock material is passed through the press between the rotating die and anvil. A pressure assist roll or a load carrying truck or tractor assembly is often employed to exert a downward force on the rotating mandrel supporting the hole punching die, causing the die to bear down against the anvil roll. As the material is passed between the rotating hole punching die and anvil roll, each of the individual hole punch inserts mounted in the die assembly cut a hole through the material. Prior art hole punching die assemblies such as that described are often used in cutting holes along the margins of paper as well as in other applications.
Prior art rotary hole punching die assemblies are disadvantaged in that each of the individual hole punching inserts mounted in the die assembly must be individually radially adjusted. Each of the individual hole punching inserts are then secured in their adjusted positions in the die assembly by tightening down the separate set screw for each insert. This set-up procedure is very exacting and is very time consuming.
Moreover, because each of the individual hole punching inserts mounted in the die assembly is held in its adjusted position by its own set screw, any one of the inserts could potentially cause damage and down time to the die cutting press by working loose from the die assembly and falling into the workings of the press. Furthermore, because the speed of rotation of the mandrel in cutting operations is often very high, should one of the hole punching inserts work loose from the die assembly, it could be thrown from the rotating mandrel and cause serious physical injury to a press operator standing nearby.
Accordingly, it would be advantageous to provide a rotary hole punching die assembly that quickly mounts a plurality of hole punch inserts on the die assembly with each of the individual inserts having a preset radial height adjustment. Furthermore, it would also be advantageous to provide a rotary hole punching die assembly in which the individual hole punching inserts mounted in the assembly could not be removed from the die assembly, either intentionally or inadvertently, without first removing the entire die assembly from the rotary cutting press, and then disassembling the die assembly at a work bench remote from the rotary cutting press. Such a rotary hole punching die assembly would substantially reduce the set up time for mounting the plurality of hole punch inserts at a desired predetermined radial height on the die assembly, and such a die assembly would substantially reduce the possibility of a hole punch insert working loose from the die assembly during cutting operations and causing damage to the cutting press or injury to the press operator.